Molded material and method of preparation



Patented Dec. 26, 1922.

srnrss AT-ET oFFi LAWRENCE E. BARRINGER, 0F SCHENEGTAIDY, NEW YORK, ASSIGNOR T0 GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

MOLDED MATERIAL AND METHOD 01E PREPARATION.

No Drawing.

To all whom it may concern;

Be it known that I, LAWRENCE E. BAR- RINGER, a citizen of the United States,- residing at Schenectady, county of Schenectady, State of New York, haveinvented certain new and useful Improvements in.

' the manufacture of electrical insulators.

It is the object, of my invention to improve products of this class both by the more uniform and thorough distribution of a binder, and also a more complete purification of the material than was heretofore practicable.

In accordance with my invention fibrous materials when cleaned from conducting particles are converted to sheet form,that is to a paper or cloth. The sheet material is coated with a suitable binder, which hardens at room temperature but is capable of being softened by heat. The coated product is shredded and finally compacted by pres sure to desiredforin.

My invention is particularly applicable to the manufacture of molded asbestos products. There is a considerable amount of undesirable matter in native asbestos min-- eral, particularly iron oxide, which'is a fairly good cond tor and is removable only with the greatest difliculty. When the asbestos is converted to a pulp and admixed with acids for chemical purification, a fiocculent fibre is produced which is mixed with a binder with difficulty. By coating the material in sheet form the most complete and uniform distribution of the binder is secured and less binder required for 'a given quantity of fibrous material.

In'carrying out my invention, and other fibrous materials, cleansed, then converted into paper form and coated with shellac or natural or synthetic resins as bakelite, or with varnish,

asbestos,

Application filed March 31,1922. Serial No. 548,535.

or other suitable binding material which normally becomes hard at room temperature, but possess plasticity at high temperature. be called thermoplastic materials.

The coated paper 'or fabric, is shredded mechanically by suitable. mechanism, such,

for example, as machines containing revolving knives and known to the trade as rotary cutters or shredding machines. The subdivided material finally is compressed in molds with or without admixture of fillers, or additional binders. To obtain the proper results the mold should be heated to the softening temperature of the binder.

Various other materials now used in molded compositions in an impure condition and not easily mixed with binders because of their physical condition, to advantage, may be converted to sheet form and then coated and shredded in accordance with my invention. Wood fibre and cotton fiock are examples. These materials can readily be purified chemically before conversion to a paper or cloth.

.Waste material resulting from factory processes utilizing coated fabric may be uti- 2. The method of making molded material which consists in coating fibrous material in sheet form with a thermoplastic material, then subdividing said sheet material and finally molding the product under heat and pressure.

3. The method of making molded asbestos i products which consists in coating sheet asbestos with a binder which softens at elevated temperature, shredding the coated product and molding the shredded material under pressure at the softening temperature of said binder.

In witness whereof, I have hereunto set my hand this 30th day of March, 1922.

LAWRENCE E. BARRINGER.

In general, binders of this class may 

